The invention relates generally to surgical power tools such as electric-motor-driven drills, bone saws and screwdrivers. To be more precise, the invention relates to a surgical power tool comprising an actuation assembly having a force sensor.
For several decades a wide variety of power tools have been used by surgeons in their work. Conventional surgical power tools frequently comprise mechanical actuation assemblies having slide switches, tumbler switches or rotary knobs for controlling certain functionalities of the tools. However, mechanical actuation assemblies are sometimes disadvantageous for surgical power tools, if the tools have to be sterilized at any rate. This is due to the fact that the moving components of such assemblies are very difficult to seal against the ingress of liquid or gaseous sterilization media.
The penetration of a sterilization medium into mechanical actuation assemblies is detrimental to their operability. For this reason, surgical power tools having tumbler switches, rotary knobs or similar moving components either cannot be sterilized at all or must be serviced after a few sterilization cycles.
To improve the sterilizability of surgical power tools, or to make it possible in the first place, actuation assemblies may be equipped with a force sensor. Force sensors have a planar design and have no moving mechanical elements. For these reasons, force sensors can be installed in a simple and sealed manner below a flexible housing section of a surgical power tool.
Surgical power tools having force sensors arranged below flexible housing sections are known, for example, from U.S. Pat. No. 3,463,990 and U.S. Pat. No. 6,037,724. In the case of the power tools described in these documents, the respective force sensor is housed within a casing of plastics material which protects the force sensor against sterilization media.
Furthermore, a surgical power tool having a force sensor arranged in a metal capsule is known from U.S. Patent Publication No. 2007/0096666, the disclosure of which is incorporated herein by reference. The encapsulation protects the sensor reliably from sterilization media. To ensure the operability of the encapsulated force sensor, continuous calibration is proposed.
The object on which the invention is based is to increase the operability of known surgical power tools having force sensors.